This invention relates to a load-lock mechanism and a processing unit in a system for processing objects such as wafers as part of a step for processing semiconductor wafers.
Current trend of semiconductor processing technology shows a shift from the conventional 6 or 8 inch semiconductor wafers towards to 12 inch wafers. As a result, semiconductor manufacturing systems handling 12 inch wafers are being developed. In 12 inch wafers, the diameter and the weight of the wafers increase and all kinds of the systems related to semiconductor manufacturing become larger in size than they are now.
For example, FIG. 6 shows in plan view an example of multi-chamber processing units which can conduct plural processes one after another. The processing unit is maintained at a set vacuum. The processing unit comprises; plural processing chambers 1 each of which can conduct etching, film forming or the like on the wafers W, and a first transferring chamber 3 which can be connected to and disconnected from each of the processing chambers 1 through a gate-valve 2A and which can transfer wafers W one by one in a vacuum corresponding to the vacuum in each of the processing chambers 1. The processing unit further comprises two juxtaposed load-lock chambers 4 each of which can be connected to and disconnected from the transferring chambers 3 through a gate-valve 2B and which can be brought into a vacuum corresponding to the vacuum in the transferring chambers 3, a second transferring chamber 5 which can be connected to and disconnected from each of the load-lock chambers 4 through a gate-valve 2C and which can transfer wafers W one by one in an atmospheric pressure, and a carrier-housing chamber 6 which can be connected to and disconnected from the second transferring chamber 5 through a gate-valve 2D and which can house a carrier C for wafers W. The wafer-transferring devices 3A, 5A are respectively arranged in the first and second transferring chambers 3 and 5. Each of the devices 3A, 5A has a handling arm which can transfer wafers W one by one. The reference sign 4A in FIG. 6 indicates a temperature controlled mounting stand for mounting a wafer W. The stand 4A forms a load-lock mechanism together with the load-lock chamber 4, and maintains the wafer W at a certain temperature.
When conducting a process on the wafer W in the left carrier-housing chamber 6, the gate-valve 2D is opened, the wafer-transferring device 5A in the second transferring chamber is driven to take the wafer W out of the carrier C in the carrier-housing chamber 6, and the gate-valve 2D is closed to shut off the carrier-housing chamber 6 from the second transferring chamber 5. Then the gate-valve 2C of the left load-lock chamber 4 is opened, the wafer-transferring device 5A transfers the wafer W from the second transferring chamber 5 onto the stand 4A in the load-lock chamber 4, and the gate-valve 2C is closed. Then a vacuum-making device (not shown in drawings) in the load-lock chamber 4 is operated to bring the load-lock chamber 4 into a vacuum. After the load-lock chamber 4 is brought into a vacuum and the wafer are brought to an appropriate temperature, the gate-valve 2B is opened, the wafer-transferring device 3A in the first transferring chamber 3 is driven to transfer the wafer W in a vacuum from the load-lock chamber 4 into the first transferring chamber 3 and the gate-valve 2B is closed. Next the gate-valve 2A of the left processing chamber 1 is opened, the wafer-transferring device 3A transfers wafer W from the first transferring chamber 3 into the processing chamber 1, the gate-valve 2A is closed and the wafer W is subjected to an appropriate process such as film forming in the processing chamber 1. During the process, other wafers W undergo other processes such as etching in another processing chamber 1.
After the wafer W has finished undergoing the processing in the right processing chamber 1, the gate-valve 2A is opened and the processed wafer W is transferred into the first transferring chamber 3. Next the gate-valve 2B of the right load-lock chamber 4 which has been brought into a vacuum is opened, the wafer-transferring device 3A transfers the processed wafer W into the load-lock chamber 4 and the gate-valve 2B is closed. Then the load-lock chamber 4 is brought back into atmospheric pressure, the gate-valve 2C is opened and the processed wafer W in the load-lock chamber 4 is transferred back into the carrier C in the left carrier-housing chamber 6 through the second transferring chamber 5. During the transferring, other wafers W which have finished undergoing the processing in the left processing chamber 1 and are transferred into the right processing chamber 1 via the wafer-transferring device 3A in the first transferring chamber 3. At the same time, a wafer W to be processed next are taken out of the left carrier-housing chamber 6, and transferred through the left load-lock chamber 4 into the left processing chamber 1 where they undergo an appropriate process such as film forming.
In the above conventional processing unit, the two juxtaposed load-lock chambers 4 are arranged to serve as the connection between the vacuum area and the atmospheric area. Thus, the improvement in the xe2x80x9cthrough-putxe2x80x9d (productivity) of the unit is achieved by increasing the efficiency of transferring the wafers W, that is, by effectively using each of the load-lock chambers 4.
The drive mechanism of the wafer-transferring device 3A in the first transferring chamber 3 must be reduced as much as possible in order to minimize the amount of produced particles. Because of this, in the conventional processing units, two load-lock chambers 4 are arranged side by side so that the handling arm in the wafer-transferring device 3A can only move horizontally at the same transferring height without moving vertically. This results in the problem of the footprints of the load-lock chambers 4 being large. Furthermore, if wafers W are 12 inch in size, the arrangement of the two juxtaposed load-lock chambers 4 greatly restricts the layout of the processing chambers 1 because the wiring becomes in more layers and the number of the processes in the processing unit, that is, the number of the processing chambers 1 increases.
The object of this invention is to provide a load-lock mechanism and a processing unit which can reduce its footprint to reduce the restrictions on the layout of the processing chambers.
To achieve the above object, this invention is characterized by a feature in that a load-lock mechanism comprising; a vacuum chamber placed between a vacuum area and an atmospheric area, having a first opening facing the vacuum area, at least one pair of second openings facing the atmospheric area, and open-close mechanisms to open and close each of the second openings, at least one pair of load-lock chambers movably housed in the vacuum chamber, a supply-discharge mechanism to supply and discharge air into or out of each of the load-lock chambers, wherein each of the load-lock chamber has a first port which can communicate with the first opening, a second port which can communicate with the corresponding second opening, and a closing mechanism to shut off an interior of the load-lock chamber from an inside of the vacuum chamber when the second port communicates with the second opening.
Preferably, the first port and the second port are formed in the same horizontal plane.
Preferably, each of the load-lock chambers can be moved vertically in the vacuum chamber. In particular, a pair of the load-lock chambers are arranged vertically, the vacuum chamber has two second openings at an upper part and at a lower part, and each of the second ports can communicate with the corresponding second opening of each of the load-lock chambers, respectively.
Preferably, the supply-discharge mechanism has a passageway provided in the vacuum chamber to connect with the first port when the second port communicates with the corresponding second opening. Otherwise, it is preferable that the load-lock chamber has a supply-discharge port, and the supply-discharge mechanism has a way provided in the vacuum chamber-to communicate with the supply-discharge opening when the second port communicates with the corresponding second opening.
Furthermore, preferably, an elevating means is provided on a bottom surface of the load-lock chamber for supporting and vertically elevating an object to be processed.
Furthermore, preferably, a cooling means is provided on a bottom surface of the load-lock chamber for cooling an object to be processed when the object to be processed is housed in the inside of the load-lock chamber.